There is a growing trend for natural based products in the personal care, pharmaceutical and retail industry. Use of vegetable oils and waxes is well known in the art; however, they generally have non-pleasant sensorial properties for personal care products. As a result, formulators typically employ low concentrations of these materials in their formulations. Formulators also frequently include ingredients to enhance the sensorial performance of skin care and hair care products. Silicones are one class of materials that are well known in the art for enhancing the sensory properties of personal care products. Typically, a formulator might separately add a vegetable oil or wax and a silicone to a personal care product in order to achieve a desired sensory profile.
A number of silicone-modified fatty carboxylic acids are known in the art. Preparation of these prior art compounds included several processes, for example, a condensation reaction between siloxane containing hydroxyl groups and the carboxylic group of fatty acids. Another commonly used method includes hydrosilylation of olefinic esters in the presence of a metal catalyst. Another prior art process employed amino addition of an amino modified siloxane to the carboxylic group of a fatty carboxylic acid. Examples of these compounds and reactions are disclosed in, for example, U.S. Pat. No. 5,051,489 to O'Lenick, Jr., which discloses waxy lubricious solids prepared from silanol waxes for use in hair, skin and textile compositions. The compounds of this patent are prepared by reacting a silanol compound with a fatty carboxylic and or polycarboxylic acid, ester or anhydride. Another U.S. Pat. No. 5,136,063 to O'Lenick, Jr. presents a series of silicone fatty esters suitable for applications in the treatment of textile and fibers. These compounds are prepared by way of a condensation reaction between the hydroxyl containing siloxane polymer and fatty carboxylic acid, ester or anhydride. U.S. Pat. No. 5,115,049 discloses fatty carboxylic acid salts of organofunctional silicone amines. The synthesis of these compounds is performed via amino addition, where a silicone amine is neutralized by a fatty carboxylic acid. EP 0955340 discloses liquid silicone esters or blends prepared by means of hydrosilylation for use in personal care and textile softening compositions. U.S. Pat. No. 4,912,242 discloses a process for the preparation of silicon esters through the hydrosilylation of allyl esters using a metal complex catalyst. U.S. Pat. No. 4,725,658 to Thayer et al discloses silicone esters prepared by hydrosilylation of fatty esters instead of fatty acids.
Another disclosure of silicone-modified fatty acids includes U.S. Pat. No. 3,563,941, which presents a silicone-carnauba copolymer synthesized by epoxy addition of an epoxy containing siloxane to the free hydroxyl groups present in the carnauba wax. The process of this patent utilizes carnauba wax containing unreacted hydroxyl radicals. The hydroxyl radicals react with epoxy groups of the silicon-containing compounds to form silicone-carnauba wax copolymer.
In the present invention, however, it has been found that there are multiple benefits that can be obtained by first reacting a silicone with a fatty carboxylic acid and then incorporating this material into a personal, hair & skin (i.e., cosmetic composition), automotive, hard-surface, or textile enhancing composition.
An object of the present invention is therefore to provide a silicone-modified fatty carboxylic acid, i.e., silicone fatty esters, capable of imparting improved sensorial feeling on, for example, the skin or hair.